The marsh warbler (Acrocephalus palustris) is an Old World warbler currently classified in the family Acrocephalidae. It breeds in temperate Europe and the western Palearctic and winters mainly in southeast Africa. It is notable for incorporating striking imitations of a wide variety of other birds into its song.

The marsh warbler breeds in a variety of mostly damp habitats, but in Africa winters mainly in dry, well-vegetated areas. It is common over much of its breeding range and expanding its distribution in some areas. However, in Britain it is now virtually extinct as a breeding bird, though the reasons for its decline are unclear. This insectivorous warbler can be easily confused with several close relatives, but the imitative song of the male is highly distinctive.

Taxonomy

The marsh warbler was formally described in 1798 by the German naturalist Johann Matthäus Bechstein under the scientific name Motacilla s. Sylvia palustris.

The type locality is Germany. The marsh warbler is now one of around 40 species placed in the genus Acrocephalus that was introduced by Johann Andreas Naumann and his son Johann Friedrich Naumann in 1811. The genus name Acrocephalus is . It is possible that the Naumanns thought akros meant . The specific is from Latin and means . The species is considered as monotypic, and there is no significant geographical variation. The sexes are alike in appearance. Hybridisation with both reed warbler and Blyth's reed warbler has been occasionally recorded. In some areas, such as Bulgaria, marsh warblers suffer significant levels of parasitism by common cuckoos.

Food and feeding

The marsh warbler is mostly insectivorous, but also takes some spiders and small numbers of snails. It generally gleans insects from vegetation but sometimes catches them on the ground or in mid-air. In autumn small numbers of berries may be eaten. There have been no detailed studies of the bird's diet in Africa, though foraging techniques during winter are known to be very similar to those in other seasons.

In Britain the species was never widespread, and disappeared from many areas from the 1930s onwards. This population was effectively extinct by the end of the 1990s. From the 1970s and 1980s onwards, a very small population slowly developed in south-east England. However, this population is also now close to extinction. The reasons for the population decline in Britain are not completely understood, despite there appearing to be much suitable habitat. The Biodiversity Action Plan for the species further comments that it is not clear what can be done to conserve the species apart from protecting habitat at known breeding sites and protecting birds from egg collectors and from disturbance.

References

Further reading

  • Vinicombe, Keith (2005) ID in depth: Marsh Warbler Birdwatch 155:30-32
  • British Trust for Ornithology page
  • UK National Action Plan
  • Marsh warbler - Species text in The Atlas of Southern African Birds